Asthma Flashcards
What is asthma?
- A chronic inflammatory airway disease characterised by intermittent airway obstruction and hyperreactivity.
- It is a disease of small airways with variable expiratory airflow limitation
- Inflammation is reversible spontaneously or with treatment
What are some precipitating factors that can trigger asthma? Name two drugs.
- NSAID’s, beta blockers
- Allergens, dust, smoking, cold weather, exercise, infection, aerosols
What 3 factors contribute to airway narrowing in asthma?
- Bronchial muscle contraction
- Mucosal inflammation and swelling - triggered by mast cell and basophil degranulation resulting in release of inflammatory mediators
- Increased mucus production
What are some symptoms of asthma?
Intermittent dyspnoea, wheeze, dry cough (nocturnal),
scanty white sputum production, SOB, chest tightness , atopy
What are some signs of asthma?
Tachypnoea, audible widespread polyphonic wheeze, hyperinflated chest, hyper-resonant percussion, reduced air entry,
What are the two features of a mild asthma exacerbation?
- No features of severe asthma
2. PEFR >75%
What are two features of a moderate asthma exacerbation?
- No features of severe asthma
2. PEFR 50-75%
What are the four features of acute severe asthma exacerbation? Note you only need one to make the diagnosis…
- PEFR 33-50% of best or predicted
- Cannot complete sentences in one breath
- Respiratory rate >25/min
- Heart rate >110/min
What are the four features of life threatening asthma? Note you only need one to make the diagnosis…
- PEFR <33% of best or predicted
- Sats <92% or ABG pO2<8kPa
- Cyanosis, poor respiratory effort, near or fully silent chest
- Exhaustion. confusion, hypotension of arrhythmias
(Normal pCO2)
What distinguishes a life threatening asthma exacerbation to near fatal?
Near fatal asthma exacerbation, the patient will have a raised pCO2
A patient has come into hospital with an acute exacerbation of asthma, what investigations would you do (4)?
Bloods - FBC, U+E, CRP, cultures
PEF - But may be too ill
aBG - If shows life threatening features/O2 sats <92%
CXR - If suspicion of pneumothorax, infection or life threatening attack
What is the immediate management of an acute exacerbation of asthma?
- ABCDE assessment
- Supplemental O2 to keep O2 sats 94-98%
- Salbutamol 5mg nebulised with O2
- Hydrocortisone 100mg IV (if PO not possible), or 40mg prednisolone STAT
- If severe, nebulised 500micrograms/6hr iprotropium bromide
Consider back to back salbutamol
What should you do when reassessing a patient after 15 mins in acute exacerbation of asthma?
- If PEF<75%, repeat salbutamol nebulisers every 15 minutes or 10mg/hr continuously
- Monitor ECG and watch for arrythmias
- Consider single dose of magnesium sulfate 1.2-2g IV over 20 minutes in severe/life threatening without good initial response to therapy
What should you do with a patient with acute exacerbation of asthma when they are not improving after 15 minutes?
- Refer to ICU for ventilation
2. Consider aminophylline and IV salbutamol
What should you do with a patient with acute exacerbation of asthma when they are improving after 15 minutes?
- Continue nebulised salbutamol every 4-6hrs and ipratropium if previously started
- Prednisolone 40-50mg PO OD for 5-7 days
- Monitor peak flow and O2 sats, aim for 94-98%
- If PEF>75% 1hr after initial treatment, consider discharge with outpatient follow up
When can you discharge a patient after acute exacerbation of asthma?
- If their PEF>75% within 1hr of treatment
OR IF AFTER ADMISSION… - Been stable on discharge medication for 24hrs
- Had inhaler technique checked
- PEF > 75% predicted and variability <25%
- Steroid (inhaled and oral) and bronchodilator therapy
- Have their own PEF meter and have a written management plan
- GP appointment within 2 days
- Respiratory clinic appointment within 4wks
A patient comes in and you think they have asthma - what investigations would you do initially?
Spirometry, and if not available do PEF.
A patient has had their spirometry and it shows a high probability of asthma - what do you do?
Trial asthma treatment.
If successful, continue at minimum effective dose. If unsuccessful, assess inhaler technique/compliance.
A patient has had their spirometry and it shows a medium probability of asthma - what do you do?
If their FEV1/FVC <0.7, try asthma treatment.
If their FEV1/FVC >0.7, consider referral/treat other cause.
What will spirometry show if a patient has asthma?
An obstructive pattern. FEV1/FVC<70%. There will be a >15% improvement in FEV1 once given a B2 agonist/steroid trial.
What will a CXR show if a patient has asthma?
Hyperinflation
What are some differential diagnoses to asthma?
Pulmonary oedema - 'cardiac asthma' COPD Large airway obstruction SVC obstruction - wheeze is constant Pneumothorax PE Bronchiectasis Obliterative bronchiolitis
What are some associated diseases with asthma?
Acid reflux
Polyarteritis nodosa
Churg-Strauss syndrome
ABPA
What are some lifestyle changes you can tell a patient with asthma to make?
Quit smoking
Avoid triggers
Weight loss if overweight
Inhaler technique - Peak flow meter to monitor PEF twice a day
Educate to enable self management by altering medication as needed
Give written action plans for an emergency
Teach relaxed breathing to avoid dysfunctional breathing
